VirtualBox is a general-purpose full virtualizer for x86 hardware. Targeted at server, desktop and embedded use, it is now the only professional-quality virtualization solution that is also Open Source Software.

Some of the features of VirtualBox are:

Modularity. VirtualBox has an extremely modular design with well-defined internal programming interfaces and a client/server design. This makes it easy to control it from several interfaces at once: for example, you can start a virtual machine in a typical virtual machine GUI and then control that machine from the command line, or possibly remotely. VirtualBox also comes with a full Software Development Kit: even though it is Open Source Software, you don't have to hack the source to write a new interface for VirtualBox.

Virtual machine descriptions in XML. The configuration settings of virtual machines are stored entirely in XML and are independent of the local machines. Virtual machine definitions can therefore easily be ported to other computers.

* Reorganization of VirtualBox into a base package and Extension Packs; see chapter 1.5, Installing VirtualBox and extension packs, see the manual for more information* New settings/disk file layout for VM portability; see chapter 10.1, Where VirtualBox stores its files, see the manual for more information* Major rework of the GUI (now called “VirtualBox Manager”):- Redesigned user interface with guest window preview (also for screenshots)- New “scale” display mode with scaled guest display; see chapter 1.8.5, Resizing the machine’s window, see the manual for more information- Support for creating and starting .vbox desktop shortcuts (bug #1889)- The VM list is now sortable- Machines can now be deleted easily without a trace including snapshots and saved states, and optionally including attached disk images (bug #5511; also, VBoxManage unregistervm --delete can do the same now)- Built-in creation of desktop file shortcuts to start VMs on double click (bug #2322) * VMM: support more than 1.5/2 GB guest RAM on 32-bit hosts* New virtual hardware:- Intel ICH9 chipset with three PCI buses, PCI Express and Message Signaled Interrupts (MSI); see chapter 3.4.1, “Motherboard” tab, see the manual for more information- Intel HD Audio, for better support of modern guest operating systems (e.g. 64-bit Windows; bug #2785) * Improvements to OVF support (see chapter 1.12, Importing and exporting virtual machines, see the manual for more information):- Open Virtualization Format Archive (OVA) support- Significant performance improvements during export and import- Creation of the manifest file on export is optional now- Imported disks can have formats other than VMDK * Resource control: added support for limiting a VM’s CPU time and IO bandwidth; see chapter 5.8, Limiting bandwidth for disk images, see the manual for more information* Storage: support asynchronous I/O for iSCSI, VMDK, VHD and Parallels images* Storage: support for resizing VDI and VHD images; see chapter 8.21, VBoxManage modifyhd, see the manual for more information.* Guest Additions: support for multiple virtual screens in Linux and Solaris guests using X.Org server 1.3 and later* Language bindings: uniform Java bindings for both local (COM/XPCOM) and remote (SOAP) invocation APIs